Production of multimodal polyethylene

A process for the preparation of polyethylene resins having a multimodal molecular weight distribution which comprises: (i) contacting ethylene monomer and a comonomer comprising an alpha-olefin having from 3 to 10 carbon atoms with a first catalyst system in a first reactor under first polymerisation conditions to produce a product comprising a first polyethylene having a first molecular weight and a first density and the first catalyst system comprising (a) a metallocene catalyst selected from one of components A or B and component A comprising a bis tetrahydroindenyl compound of the general formula (IndH4) 2R''MQ2 in which each Ind is the same or different and is indenyl or substituted indenyl, R'' is a bridge which comprises aC1-C20 alkylene radical, a dialkyl germanium or silicon or siloxane, or an alkyl phosphine or amine radical, which bridge is substituted orunsubstituted, M is a Group IVB transition metal or vanadium and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen andcomponent B comprising a metallocene catalyst of general formula R'' (CpRm) (Cp'R'n) MQ2, wherein Cp is a cyclopentadienyl moiety. Cp' is a substituted or unsubstituted fluorenyl ring;each R is independently hydrogen or hydrocarbyl having 1 to 20 carbon atoms in which O ≤m ≤ 4; each R' is independently hydrocarbyl having 1 to 20 carbon atoms in which O ≤n ≤8; R'', M and Q are each as defined above, the metallocene component B having a centroid-M-centroid angle in the range 105 DEG to 125 DEG ;and (b) a cocatalyst which activates the catalyst component; (ii) providing a second polyethylene having a second lower molecular weight and higher density than the first molecular weight;and (iii) mixing together the first and second polyethylenes to form a polyethylene resin having a multimodal molecular weight distribution.